When the temperature of the fuel is low during the cold starting of an internal combustion engine, then the injected fuel is hardly vaporized, and the fuel concentration is locally raised. On account of such a situation, it is feared that the combustion state may be deteriorated and any uncombusted fuel may be discharged.
In relation thereto, a technique is known, in which an internal combustion engine is started after heating the fuel by means of a heater provided for an accumulator or an injector (see, for example, Patent Document 1). However, it is feared that the mileage or fuel efficiency may be deteriorated, because the energy is consumed by the heater.
Further, a technique is known, in which the work of a fuel pump is increased to raise the temperature of the fuel by increasing the discharge amount of the fuel pump and releasing any excessive fuel (see, for example, Patent Document 2). However, it is feared that the mileage or fuel efficiency may be deteriorated by an amount of increase in the work of the fuel pump.